Pulmonary Surface Tension and the Mucus Lining of the Lungs: Some Theoretical Considerations

Some Effects of Restriction of Chest Cage Expansion on Pulmonary Function in Man: An Experimental Study*†

“…The smallness of the volume of nitrogen released makes it unlikely that closure of major (e.g., lobar or segmental) airways occurred, and we are inclined to believe that closure had occurred in terminal lung units. A mechanical basis for the closure and opening of such units has been described (1,24) and the phenomenon of their sequential opening has been observed in isolated animal lungs (25). Our data do not permit conclusions to be drawn on the volume of gas that might be trapped in an occluded lung unit (24,26) or on the number of units that were occluded.…”

A critical assessment of the Wilhelmy method in studying lung surfactants.

“…Two surfactants were used in this study: dipalmitoyl lecithin and an industrial detergent which has previously been used in physiological studies known as Tween 20 (Clements et al 1958 The surfactants were studied at the surface of a pool where the film area could be varied from 52-5 to 14-4 cm2, i.e. down to 27-5 % of maximum, by means of a movable barrier.…”

“…This is imperative in view of the significance attributed to these y: A loops in current theories of pulmonary mechanics in which surfactant is considered to reduce inflation pressure (Von Neergaard, 1929) and to play major roles in keeping the lungs dry and in compliance hysteresis (Pattle, 1955(Pattle, , 1958Clements & Tierney, 1965;Clements, Brown & Johnson, 1958;Mead, Whittenberger & Bradford, 1957). This study has been directed towards answering these questions by making simultaneous measurements of surface tension with both the Whilhelmy and Du Nuoy ring methods on the same DPL films over area cycles commonly employed in studies of lung surfactants.…”

Alterations in pulmonary surface active lipids during exposure to increased oxygen tension.

“…Extracts of normal lung have been shown to contain a surface active agent that by decreasing alveolar surface tension serves to stabilize the alveoli during respiration (1)(2)(3). This surfactant has been shown to contain lipid probably complexed with protein (4,5).…”